Couesius plumheus (Agassiz) Chub Minnow 

 Barbels minute; pharyngeal teeth 4-4 or 1'4'4'1; lateral line incomplete 

 in some species 170. 



170. Pharyngeal teeth in one row (4-4); scale count over 80; Gila River 



Basin 



Agosia chrysogaster Girard 

 Pharyngeal teeth in two rows (1'4'4'1) ; scale count under 80, except in 

 A. oscula 171. 



171. With ten or eleven rays in the dorsal fin 172. 

 With eight rays in the dorsal fin 173. 



172. Scale count over 60; inner rays of pelvic fins not joined to body; Idaho 



Apocope umatilla (G. &? E.) 

 Scale count under 60; inner rays of pelvic fins joined to body; Columbia 

 River Basin 



Apocope falcata (E. & E.) 



173. Scale count over 80; color greenish, with red patches about the head; 



Colorado and Gila Rivers 



Apocope oscula (Girard) 

 Scale count under 80 174. 



174. Scale count under 70; with one dark band on each side; Columbia River 



basin and coastwise streams of Wash, and Oregon 

 Apocope nuhila (Girard) 

 Scale count 70 to 80; Colorado River Basin 175. 



175. With two dark bands on each side 



Apocope yarrowi (J. & E.) 

 Dusky above 



Apocope couesii Yarrow 



176. Head flattened; scale count about 50; headwaters of the Missouri River 



and surrounding territory 



Platygohio gracilis (Richardson) Flat-headed Chub 

 Head not so much flattened above; scale count various 177. 



177. Mouth terminal; eye shorter than upper jaw 178. 

 Mouth distinctly overhung by snout; eye longer than upper jaw, except 



in M. aestivalis 179. 



178. With a round dark spot at the base of the tail fin; northward and east- 



ward from the 02;arks 



Jslocomis \entuc\iensis (Raf.) Hornyhead Chub 

 l\locomis higuttatus (Kirtland) 

 Caudal spot irregular and indistinct; eastern and east-central U. S. 

 7<locomis micropogon (Cope) River Chub 



179. Not spotted; pharyngeal teeth in two rows (1-4-4-1 or 1-4-4-0); eastern 



and central U. S. to Oklahoma 180, 



Body with dark spots; pharyngeal teeth in one row (4-4) 181. 



180. Plain silvery colored 



Erinemus storerianus (Kirtland) Silver Chub 

 Hyhopsis storerianus (Kirtland) 



278 



